The burning earth, with hot oppression curst,
Returns the heat which they imparted first.
All remedies they try, all med’cines use,
Which nature could supply or art produce:
Invincible, it mocks the vain design,
And art and nature foil’d—declare the cause divine.”
Hippocrates, the great founder and parent of rational medicine, in his book on Epidemic Distempers, accurately delineates the vicissitudes of the weather and the different seasons of the year, attributing to them the causes of all diseases. He thus describes a state of atmosphere producing a most extraordinarily dismal pestilence and mortality: A season marked by abundant showers, a south wind following drought; a hot and sultry autumn, with abundant rain; a humid, open, light, and warm winter, extremes of cold after the conversion of the sun under the equinox, with winds blowing, with snow and sudden great change of weather.
“Annus austrinus, imbribus abundans atque in totum ventis tranquillus fuit. Quum autem paulo superioribus anni temporibus justo majores siccitates viguissent, sub Arcturum sperantibus austris multum fuit. Autumnus obscurus, nebulosus, cum aquarum abundantiâ, hyems austrina humida et levis. Longo vero post solis conversionem intervallo juxta Æquinoctium, extremæ hyemes adfuerunt; jamque sub Æquinoctium ipsum Aquilonares venti cum nivibus non ita diu speravere. Ver rursus austrinum a flatibus quietum, aquæ multæ et continentes ad canem usque. Æstas verum calida, æstus præfocantes magna. Anniversarii venti (Etesias vocant) pauci disjunctim speravere. Sub Arcturum rursus spirantibus aquilonibus aquæ multæ.”—(On Epidemics, bk. iii. sect. 3.)
Again, in section 8 and 18 we have: “In aëre considerandum quanta insit caliditas, frigiditas, crassitudo, tenuitas, siccitas, humiditas an plenior an vero minor et copiosior. In quibus quænam mutationes et ex quibus fiunt, quomodoque se habeant, animadvertere oportet,”—plainly signifying that a pestilential constitution of the seasons consists of atmospheric vicissitudes, heat and cold, dryness and moisture out of season and in excess.
Galen, the great commentator on the works of his master, assigns two causes to pestilence; the one, a great irregularity of the seasons, and consequently a pestilential state of the air; the other, a vitiated condition of the human body from corrupt and defective food, impure air, &c., by which means it is rendered liable to disease: here we have the exciting and the predisposing causes of disease clearly pointed out.